v2 channel open uses a different method to derive the channel_id, so now
we save it to the database so that we dont have to remember how to
derive it for each.
includes a migration for existing channels
Previously we were annotating every movement with the blockheight of
lightningd at notification time. Which is lossy in terms of info, and
won't be helpful for reorg reconciliation. Here we switch over to
logging chain moves iff they've been confirmed.
Next PR will fix this up for withdrawals, which are currently tagged
with a blockheight of zero, since we log on successful send.
Adds a new plugin notification for getting information about coin
movements. Also includes two 'helper' notification methods that can be
called from within lightningd. Separated from the 'common' set because
the lightningd struct is required to finalize the blockheight etc
Changelog-Added: Plugins: new notification type 'coin_movement'
